1. Field of the Invention
The present disclosure relates to inertial devices, recording media, and methods for positioning.
2. Description of the Related Art
There is a technology called a pedestrian dead reckoning (PDR) system for estimating a position of a pedestrian in a situation where a global positioning system (GPS) is not available, such as at an indoor environment or in the basement, by use of measurements of an accelerometer, a gyroscope, and a magnetometer. In the PDR system, an arithmetic operation is performed on the measurements in order to estimate a traveling direction and a traveling velocity vector with respect to a pedestrian, so as to perform time integration on the traveling velocity vector of the traveling velocity in order to estimate a current position. Here, a sensor which has an integrated function of an accelerometer, a gyroscope, and a magnetometer is called a motion sensor.
With regard to an estimation of a direction in the PDR system, the traveling direction of a pedestrian is determined based on an absolute azimuth detected by the magnetometer and the gyroscope. That is to say, even though an amount of directional changes is detected by the gyroscope, a current position may not be estimated correctly unless the absolute azimuth is detected by the magnetometer.
There is a technology for improving accuracy of an estimation of the absolute azimuth by use of a map-matching method (e.g. Japanese Patent No. 5059933). According to disclosure in Japanese Patent No. 5059933, there is a technique of performing map-matching on map data with respect to a straight walking movement detected in the PDR system in order to correct a traveling direction of a user based on a direction between two positions matched on the map data.